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Published in Ebby Elahi, World Compendium of Healthcare Facilities and Nonprofit Organizations, 2021
Amplifies the patient voice of X-linked hypophosphatemia (XLH) and related disorders by connecting groups worldwide to set a global multi-disciplinary standard of care and research that could not otherwise be achieved independently, to ensure that all patients’ management is the same.
Nutritional Regulation of the Growth Plate
Published in Crystal D. Karakochuk, Kyly C. Whitfield, Tim J. Green, Klaus Kraemer, The Biology of the First 1,000 Days, 2017
Genetic studies in mice have provided important insights into the molecular mechanisms by which vitamin D deficiency impairs childhood bone formation and growth. Targeted ablation of vitamin D receptor (Vdr) in mice leads to hypocalcemia, hyperparathyroidism, hypophosphatemia (due to hyperparathyroidism), and rickets [34]. However, prevention of abnormal mineral ion homeostasis in Vdr-null mice using a high-calcium and high-phosphorus diet has prevented the development of rickets, suggesting that impaired mineral ion homeostasis, rather than Vdr-mediated signaling itself, is the primary cause of impaired bone growth [35]. Importantly, mutations in PHEX in mice, which causes hypophosphatemia (but only slightly lower calcium), and mice fed with a low-phosphorus high-calcium diet, both developed rachitic bones [36]. Similarly, children with X-linked hypophosphatemia, which results from increased urinary phosphate excretion, have decreased phosphorus but normal levels of calcium and vitamin D in blood, but also developed rickets and short stature. Taken together, evidence from mouse models and human disease collectively suggest that impaired growth in rickets is primarily caused by phosphate deficiency, rather than the lack of vitamin D or calcium per se.
Musculoskeletal (including trauma and soft tissues)
Published in Dave Maudgil, Anthony Watkinson, The Essential Guide to the New FRCR Part 2A and Radiology Boards, 2017
Dave Maudgil, Anthony Watkinson
Are the following statements true or false? Enthesopathy may occur with: X-linked hypophosphataemia.acromegaly.Reiter’s disease.scurvy.degenerative disease.
Endocrine fibroblast growth factors as potential biomarkers for chronic kidney disease
Published in Expert Review of Molecular Diagnostics, 2020
Yuichiro Kondo, Hirotaka Komaba, Masafumi Fukagawa
Circulating FGF23 levels can be measured with either an intact FGF23 assay that detects intact FGF23 alone or with a C-terminal assay that detects intact FGF23 as well as C-terminal fragments. The intact FGF23 assay uses two monoclonal antibodies that recognize the C-terminal region of FGF23 (amino acids 180–194) and the three-dimensional structure of N-terminal FGF23. By contrast, both antibodies of the C-terminal assay recognize epitopes located within the C-terminal region of FGF23 (amino acid residues 206–222 and 225–244). In general, the intact FGF23 assay is considered to be superior to the C-terminal assay, as only the full-length FGF23 is biologically active. Indeed, it was reported that the intact FGF23 assay allows a more accurate diagnosis of hypophosphatemic osteomalacia such as XLH and TIO compared with the C-terminal assay [39], and intact FGF23 level of more than 30 pg/ml together with hypophosphatemia is accepted as one of the diagnostic criteria of these diseases [40]. It is however noteworthy that measurements of C-terminal FGF23 levels together with intact FGF23 levels help provide an estimate of FGF23 transcription and cleavage [41].
A novel method for observing proportional group awareness and consensus of items arising from list-generating questioning
Published in Current Medical Research and Opinion, 2020
Any process to obtain consensus from a group of experts would benefit from understanding awareness of items on which a later consensus is to be formed. The four case studies about X-linked hypophosphatemia (XLH) are reported to demonstrate the principle of group “awareness” of items and its relationship with consensus on items retention. XLH is a rare, hereditary and progressive disorder affecting around 1 in 20–25,000 individuals and is characterised by phosphate wasting mediated through elevated levels of circulating fibroblast growth factor (FGF) 23, resulting from mutations in the phosphate regulating endopeptidase homolog, X-linked (PHEX) gene5–8. Paediatric patients with XLH typically present with complications such as impaired and disproportional growth, progressive bowing of load bearing limbs and rickets, before developing issues such as osteomalacia, hearing deficits, musculoskeletal dysfunction and dental complications as adults9,10.
Treatment of fibrous dysplasia: focus on denosumab
Published in Expert Opinion on Biological Therapy, 2022
Bogdan Huzum, Sabina Antoniu, Raluca Dragomir
Burosumab is a monoclonal antibody targeting FGF-23. It has been approved in the United States for the treatment of X-linked hypophosphatemia and for tumor-induced osteomalacia [45]. Given that FD hypophosphatemia is also a pathogenic feature and is the result of increased renal excretion, burosumab might represent a potential therapeutic agent that might successfully address the limitations of vitamin D and phosphorus supplementation, which are hypercalciuria and gastrointestinal intolerance [46]. Case reports on the use of burosumab in FD are being published. Larger case series are expected to be reported in the near future. One case report described a 7-year-old boy with severe FD/MAS diagnosed during the first year of life. The hypophosphatemia was initially responsive to phosphate supplementation and calcitriol, but with rapid development of feeding problems and subsequent bilateral nephrocalcinosis and hypercalciuria. He had bone involvement throughout his body and developed 17 fractures and various deformities as sequelae, beginning at the age of 7 years. At the age of 4 years, he received a bisphosphonate infusion. This resulted in Fanconi syndrome. The next dose was stopped. Burosumab was administered after detection of elevated serum FGF-23 levels. A 20-mg dose was administered every 2 weeks for 17 months. This regimen decrease pain and improved functional status after the first dose. Bone imaging did not detect baseline abnormalities, and no adverse events were evident [47]. Further studies are needed to evaluate the efficacy and safety of burosumab. It is worth mentioning that this therapy is not able or has not yet been demonstrated as being influential for abnormally increased osteoclastogenesis. Thus, the therapy might be reserved for the pathogenic treatment of FD/MAS ‘satellite’ abnormalities, such as hypophosphatemia.